Inspector12

iTrader: (29)

The cam desision should be thought of when the design of the turbo system is picked out IMO. A general cam will probably work for what your goals are (Street use), but depending on if it is a headers designed single or twins or some kind of log setup or even a manifold setup it should be taken into account as I have ran into reversion on restrictive logs and had to use a cam with almost no overlap at all or it would fall on its face in the higher RPMs @ 4500 or so etc... I agree if packaging is an issue you might think about a stock stroke crank to keep the cubes down where twin 60-67's could be used for that size motor and your power goals are easily achieved with even a 346 so the cubes aren't necessary to make 750rwhp Mightymouse is just one example of that as well as KP and me as well, but most don't know I am running a 346 in my procharged car currently. Just some options for you as it doesn't sound like you have any definative plans just tossing them up so I thought I'd throw a wrench in there for you to contemplate LOL! Also from experience the aftermarket heads are alot better at not deflecting under boost than factory heads although if you are set about your power goals a factory ported head of any kind will handle those power requirements easily if you think you are going to save a significant amount of money ,although I would still buy an aftermarket head and minimum a set of ARP 2000 head studs.

lw.jordan

iTrader: (16)

I already have the ARP head studs; and actually to be honest, the main reason i chose the 806 heads was because they were cheaper.. and thanks for yet another wrench lol.. having an end goal when popping so many cherries(if you will) like this seems to be an achilles heel of sorts.
maybe sell the 427 block, use the 60-1's on the stock engine, plus a forged rotating assembly is the way to go?

98Z28CobraKiller

iTrader: (17)

+1 about the cam. I was suffering from some insomnia last night. I said that for a street car you want atleast a couple degrees of overlap were I meant to say negative overlap.

I personally prefer less stroke. I've had a bunch of bad luck with 4.00" stroke cranks. I know, I know. There are thousands upon thousands of 4.00" stroke motors out there that are supposedly just fine but my personal experience has not been good. That said, if you aren't pushing it hard and have already spent the coin to go that way, stick with it. those turbos with 2 different housings on them dont sound like a good idea to me on any motor. I say keep the motor and lose the turbos. If cost is a concern, buy a single like one of those S480's. They are under $1K bucks, have a T6 flange and will probably still get you to 1000 rwhp without too much trouble with those cubes. It should make retarded amounts of torque also.

lw.jordan

iTrader: (16)

I'm glad I asked about all this. You guys have been super helpful. Looks like it's back to the drawing board. At least the engine internals are coming out of the haze a bit. I was thinking either the tsp texas giant or the gt7 for a cam. should that vary with the decision for twin/single turbos?

Adam Connell

Welcome to the LS1tech "Bigger is better" school of thought...

You have done the math, and you know what your goals are.

If this is a street car, you want the SMALLEST turbos you can get away with to give you the best street manners possible. Turbo lag is the enemy.

I would also go with ball bearing turbos. You might want to call up precision and talk to them about their new air cooled ball bearing turbos.

I hate to say it, but I do not think you are going to find the information you are looking for here... I have been here for a while and from what I have seen most people just slap on a turbo and go without much consideration to street manners.

Rob@ChampionMotors

-427 with 9.0 compression
-twin 60-1 with .81 A/R exhaust housings @15 lbs should make at least 800-850 rwhp.
-custom turbo cam in the 230's intake / 220's exhaust on a 117
Give us a call if you need more info.
Rob.
416 751-8047

r.barn

Twin Turbonetics 62-1 with the .81 a/r would be perfect.

The 62-1 feeds about 10% more air than the 60-1.
Maxes out at about 62 lbs/min

427 running 6,500rpm and 85% Ve at 15psi will need 100-120 lbs/min
and will easily make 800-900rwhp.

So (2) 62-1's should work nice. With the .81 a/r that Turbonetics offers
you will get a little better spool than the .96 a/r.

If you dont care about breaking 1000rwhp, then you have a really good plan.

lw.jordan

iTrader: (16)

I looked at forcedinductions.com at the consumption chart for a 427 and at 6500rpm/15psi, the consumption is what I calculated on my own(90lbs). Looking at the compressor map and splitting the supply evenly between the turbos, 45lb/min is just barely outside the peak efficiency for the 60-1's. If what you(Champion, r.barn) both say is true, can you give some insight about why the rest of the guys that have chimed in have said these 60-1's are too small? I still feel some further discussion would benefit this decision making process.
As for the 806 heads, I agree 100% on upgrading to AFR225's.

Champion, the cam specs you've mentioned seem a bit of reverse logic from what I have seen so far. My understanding is, the more lobe separation, the less street friendly. Also the intake and exhaust numbers are reversed. It seems to me that a longer exhaust duration would increase performance based on valve sizing and lift; especially with little to no overlap. Am I thinking correctly?

98Z28CobraKiller

iTrader: (17)

Those cams are a little larger than I was thinking.

Big turbos dont hurt street manners. A little lag on a 427 wouldn't be the end of the world. Regardless, I have a buddy with a 408 and twin 66's (non ball bearing) and they spool instantly. The OPs turbos are way too small.

Feel free to add specifics rather than just make general comments about the site in general and the lack of knowledgeable people wandering about aimlessly within.

ninetres

iTrader: (35)

Have you been getting my PMs? I have not heard back from you.

lw.jordan

iTrader: (16)

yeah man, i've just been doing a TON of reading/research. I don't want to repeat any mistakes nor make any more with this build.. I do make good money, but that doesn't mean I want to throw it away. I'll give you some time tonight and I PROMISE to get back with you soon.

lw.jordan

iTrader: (16)

oh.. and for everyone else following the thread.. tre has a th400 i am looking at swapping out my t56 so I can take advantage of a stall to spool the turbos off the line.. hijacker
So Killer, you're still adamant about the 60-1's being far too small for the 427 application? It looks like, as far as a twin setup is concerned, that t70's would work much better; any thoughts on the single vs twin option? I think there's an s91 and also an s480 up for sale right now in the classifieds.

Inspector12

iTrader: (29)

I didn't say they were too small, but I will tell you I had twin GT67's on my 8.5:1 402 and they spool INSTANTLY! I had to use my Eboost2 Gain to slow the ramp rate to help the lack of traction. Street cars I know about cause that is all mine are race cars I have some knowledge, but not nearly as much as a lot of others on this site and some of the shops. So I will agree with cobrakiller and say a little lag or traction control isn't a bad thing for a street car espesially from a dead stop, but you can use a boost controller to help keep the boost from hitting so hard with small turbos, but they will run out of steam up top. But like I said earlier if packaging is a concern then small turbos are easier to fit into tight places, and they will meet you power goals. I think cobrakiller is just trying to help you from his own experiences, but your plan would work just not ideal. So far be it for me to tell you how to build your car as everyone had to do there own thing just offering a little insight from my own setup experiences. GL!

lw.jordan

iTrader: (16)

Oh, I am by far not trying to argue one point or the other; I am merely trying to gather info from as many as I can, from their experiences, so that I can make a more informed decision. I just sold my Eboost2 in favor of using the on-board boost controller provided with the megasquirt system. Room for me should not be an issue. I am relocating my battery, have already deleted my ABS for a line lock and proportioning valve, and have no qualms about replacing and relocating the radiator further forward. I may even junk the refrigerant cooling idea and delete the AC for some added space.. but that sure does interest me as far as performance.. and I don't know of anyone else on this forum(so far) that has tried or uses that idea. Obviously, for a single shot down the track, that would be overkill, but for a cruise, I think very beneficial.. I may start another thread to spur some discussion on that topic..
I definitely appreciate all your inputs.. like I said, I am popping so many cherries with this project.. but, eat an elephant one bite at a time right?

r.barn

I think it just comes down to matching turbos for intended power goals.

If you think you will ever get the itch to bust 1000rwhp then I would
do some a pair of Precision 67's ..... if 800-900rwhp is more than enough
to scare the crap out of you then a pair of 62's will do that easy, cost less
and spool better.

If it was my build ......

402-408 @ 9.0 c/r
225 ported heads
Custom turbo cam
1 3/4 primary turbo headers
twin 3" downpipes
twin Tial 44mm wategates
Twin Garrett GT4088's
http://www.turbobygarrett.com/turbob...8_703457_2.htm

Make 850 at low boost and well over 1100+rwhp at the push of a button
Zoom

ninetres

iTrader: (35)

Not that it will help you this instant but my re-build that is underway for my 370ci will be utilizing twin borg warner 60mm. They will be on full tilt. Hoping to make 1100+rwhp

lw.jordan

iTrader: (16)

well tre... i know where you could get a pair of 60-1's for a reasonable price

r.barn... I'm not sure what's going to "scare the crap" out of me.. I know that after laying my bike over last summer(lots of fractures and road rash involved) I'm a bit skiddish on curves, no matter what I'm in.. but as far as straight line, nothing thrills me more than to be slammed into the seat when I hit the throttle.
I honestly would like to stop when I am required by NHRA to have a parachute.. boost, motor, spray, whatever it takes.. parachute is the goal.

Black_Phantom

precision billet 6765's **** load of power on 427 spool fast, way more power on low boost, Evo guys making about 900hp on single one of those.
Do it right the first time because Turbo is addiction and YOU WILL UPGRADE your Turbos down the road.
Good luck with your build man

98Z28CobraKiller

iTrader: (17)

You have to make a decision (and stick to it) as to which components you want to keep and which you want to scrap. Then you can go forward from there.

1) keep the turbos and go to less cubes.
2) keep the motor and go to bigger twins
3) keep the motor and go to a big single

Either way, buy a good set of aftermarket heads with a thick deck.

Personally, I'm very budget minded so I would go for most bang for the buck depending on what's available out there.

As for the S480 vs the S91. Both those turbos would work great. The S91 would make a good bit more power but either will get you to your goal. The 480 should be alot cheaper.

ScorpionT

The 60-1's with P trim turbine will work fine for your setup. The turbine will flow enough, and the compressor can keep up and still be efficient. If you want a little more punch, the 62-1 or Precision billet 6265's will do the job. If you want to go a little more crazy, the billet 6765's like Black Phantom said (capable of 1200+whp).

The S91 is overkill, but the S480 would be just right.